Snap acting valve for gas burners and the like



Jan. 25, 1966 R, SCHQRK ETAL 3,230,973

SNAP ACTING VALVE FOR GAS BURNERS AND THE LIKE Filed June lO, 1965 2Sheets-Sheet 1 F76. F/G. 4

w ,f3 f/f mn\\ 77 a /f/a in@ IIIIFr Jan 25, 1966 R. scHoRK ETAL3,230,973

SNAP ACTING VALVE FOR GAS BURNERS AND THE LIKE Filed June lO, 1963 2Sheets-Sheet 2 F76. 7 F7C?. /0

United States Patent O 3,230,973 SNAP ACTING VALVE FR GAS BURNERS ANDTHE LIKE Rudolf Schot-lr, Wem-au, and Kurt Steinhardt, Stuttgart-Sllenbuch, Germany, assignors to Junkers & Co.

G.m.b.H., Wernan, Germany Filed June 10, 1963, Ser. No. 286,753 Claimspriority, application Germany, June 9, 1962, J 21,919, J 21,920; Feb.25, 1963, J 23,241 5 Claims. (Cl. 137-625.253)

The present invention relates to valves in general, and moreparticularly to a valve which is especially suited for deliveringcontrolled quantities of fuel to multi-stage gas burners. Such burnersmay be used in gas ranges, in water heaters and in similar appliances.

It is known to provide a valve in the path of fuel ow to the main burnerof a water heater and to construct the valve in such a way that it maydeliver a small stream of gaseous fuel prio-r to permitting the passageof a larger fuel stream. In other words, when the valve is actuated,

it permits a small stream of gaseous fuel to ow towardv the burner and,once this small stream is ignited, the valve permits a larger stream toow and to be ignited by the smaller fuel stream. A serious drawback ofconventional valves of this general character is that the-re is a delaybetween the time when the valve starts the discharge of a smaller streamand the time when the small stream is permitted to flow at fullcapacity. Such construction is particularly unsatisfactory when theso-called Wobbe number of the gas is high. The Wobbe number isdetermined by dividing the caloric value with the square root 0f thedensity of the gas.

Accordingly, it is an important object of our invention to provide avery simple valve which is consrtucted and assembled in such a way thatthe flow of one or more small streams of gaseous fuel to the burner maybe increased instantaneously or nearly instantaneously from zero to fullcapacity. l

Another object of the invention is to provide a valve of the justoutlined characteristics wherein the flow of a large gas stream may alsoincrease from zero to full capacity practically without any loss in timeand in timed relation to the full-capacity iiow of one or more smallergas streams.

A further object of the invention is to provide a valve of the justoutlined type wherein the customary sealing element is mounted in such away that it actually assists in increasing the rate of fuel tiow fromZero to full capacity without any or with exceptionally short delay.

An additional object of the invention is to provide a gas valve whichembodies the above outlined features and which may be combined withconventional multi-stage burners without necessitating any changes inthe construction of such burners.

With the above objects in view, one feature of our invention resides inthe provision of a valve which is especially suited for controlling theflow of fuel to a multistage gas burner. The valve comprises a firstvalve member having a bore bounded by an internal surface and a secondvalve member having a peripheral surface spaced from and defining anannular gap with the internal surface of the stationary valve member.The second valve member is movable axially in a rst direction from theone toward the other end of the bore into a valve closing position andin a second direction counter to such first direction to assume a valveopening position. One of the valve members has at least one bypassopening which communi-Cates with the gap when the second valve memberassumes its valve closing position, and the valve further comprises anormally compressed elastic sealing ring `which is received in the gapand which is secured to the ICC other valve member so as to engage thesurface of the one valve member between the bypass opening and one endof the bore when the second valve member assumes its valve closingposition. In accordance with our invention, the surface of the one valvemember (i.e., of that valve member which is provided with one or morebypass openings) has a first annular portion adjacent to the bypassopening and a second annular portion immediately preceding the firstannular portion as seen in the direction of movement of the second valvemember to its valve opening position.. The lirst annular portion is moredistant from the other valve member than the second annular portion sothat the second annular portion constitutes an obstruction to movementof the second valve member and that, when the second valve member movesin a direction to assume its valve opening position, the ring iscompressed more while engaging the second annular portion and is thenpermitted to expand toward the first annular portion with simultaneousreduction in its resistance to movement of the second valve member toits valve opening position whereby the bypass opening is exposed almostinstantaneously in an intermediate position of the second valve memberand permits a small stream of fuel to flow to the burner at fullcapacity. In its valve opening position, the second valve member permitsa larger stream of gaseous fuel to ow from the one to the other end ofthe bore in the stationary valve member, and such large stream may beignited by fuel which was delivered through the bypass opening.

The novel features which are considered as characteristie of theinvention are set forth in particular in the appended claims. Theimproved valve itself, however, both as to its construction and its modeof operation, together with additional features and advantages thereof,will be best understood from the following detailed description ofcertain specific embodiments with reference to the accompanyingdrawings, in which:

FIG. l is a fragmentary axial section through a valve which embodies oneform of our invention and whose movable valve member is shown in valveclosing position;

FIG. 2 is a similar section showing the movable valve member in anintermediate position in which a small stream of gaseous fuel ispermitted to flow through a bypass opening provided in the stationaryvalve member;

FIG. 3 is another fragmentary axial section showing the movable valvemember of FIGS. l and 2 in valve opening position;

FIG. 4 is a fragmentary axial section through a modied valve Whosemovable valve member is provided with a bypass opening and is shown invalve closing or sealing position;

FIG. 5 illustrates the structure of FIG. 4 with the movable valve memberin an intermediate position in which the bypass opening permits a smallstream of fuel to flow to the burner;

FIG. 6 illustrates the structure of FIGS. 4 and 5 with the movable valvemember in a valve opening position in which the valve permits a largestream of fuel to flow to the burner;

FIG. 7 is a fragmentary axial section through a third valve which issimilar to the valve of FIGS. 1 to 3 and whose valve member is shown invalve closing position;

F IG. 8 illustrates the structure of FIG. 7 with the movable valvemember in an intermediate position in which a small stream of fuel ispermitted to ow through a bypass opening provided in the stationaryvalve member;

FIG. 9 illustrates the structure of FIGS. 7 and 8 with the movable valvemember in valve opening position;

FIG. l0 is a fragmentary axial section through a fourth valve which issimilar to the valve of FIGS. 4 to 6 and whose movable valve member isshown in one of its end positions in which the valve is closed so thatthe source of gaseous fuel is sealed from the burner;

FIG. l1 is a similar fragmentary section showing the movable valvemember of FIG. l in an intermediate position in which a bypass openingprovided in this valve member permits a small stream of fuel to flow tothe burner; and

FIG. 12 illustrates the structure of FIGS. 10 and l1 with the movablevalve member in valve opening position in Which it permits a largestream of fuelto flow to the burner.

Referring to the drawings, and first to FIGS. 1 to 3, there is shown avalve which is especially suited for selectively delivering a largestream `or one or more smaller streams of fuel to a multi-stage gasburner. This valve comprises a stationary valve member which defines anannular seat 11, and a movable valve member 12 which carries an annulargasket 13 adapted to move into and out of sealing engagement with theannular end face 11a of the seat 11. The movable valve member 12comprises an extension 14 which is normally received with play in athrough bore 15 of the stationary valve member 10 so that the internalsurface of the valve member 1i) which surrounds the bore 15 defines withthe peripheral surface 14a of the extension 14 an annular gap 16 whichaccommodates a portion of an annular sealing ring 17, the latterconsisting of elastically deformable material (e.g., rubber or syntheticplastic) and being dimensioned in such a way that it is compressed bythe internal surface of the stationary valve member 10 to provide areliable seal between the lower or intake end of the bore 15 and abypass opening 18 which communicates with the upper or discharge end ofthe bore 15 via gap 16 when the valve member 12 assumes the valveclosing position of FIG. l. The bypass opening 13 comprises a radialsection and an axially extending section, and the latter communicateswith a shallow recess 11b which is surrounded by the seat 11 and whichcommunicates with the upper end of the bore 15. The inner portion of thering 17 is received in an annular groove 1411 provided in the peripheralsurface 14a so that the ring 17 is compelled to share axial movements ofthe valve member 12 when the latter is caused to leave the position ofFIG. 1 and to advance through the intermediate position of FIG. 2 towardand into the valve opening position of FIG. 3. In other words, the valvemember 12 is movable in a first direction axially of and from the uppertoward the lower end of the bore 15, and in a second direction counterto such first direction and in a sense to withdraw its extension 14 fromthe bore 15, see FIG. 3.

In accordance with an important feature of our invention, the stationaryvalve member 10 is formed with an annular obstruction or bead which isclosely adjacent to the bypass opening 18 and which is located ahead ofthis opening, as seen in the direction in which the valve member 12moves when its extension 14 is being with drawn from the bore 15. Theobstruction 20 is of semicircular cross-sectional outline and is boundedby a convex surface which includes a lower section 21 normally abuttingagainst the ring 17 in the valve closing position of the member 12 andan upper section 22 which is immediately adjacent to the opening 18. Thesections 21, 22 together constitute a portion of the internal surface ofthe valve member 1t), and this surface is nearer to the peripherialsurface 14a than a second surface portion which extends from the surfaceportion 21, 22 toward the upper end of the bore 15.

The valve of FIGS. l to 3 operates as follows:

In FIG. 1, the valve member 12 is shown in valve closing position inwhich its gasket 13 abuts against the end face 11a of the seat 11 and inwhich its ring 17 abuts against the internal surface of the valve member10 including the section 21 so that both ends of the bypass opening 18are sealed. In other words, the horizontal symmetry plane of the ring 17is located at a level below the apex of the obstruction 20. At the sametime, the gasket 13 cooperates with the ring 17 to provide a reliableseal against escape of fuel which tends to flow upwardly, as viewed inFIG. 1, through the lower end of the bore 15, through the gap 16, andtoward the upper endof the bore 15. It is assumed that the lower end ofthe bore 15 is connected with a source of gaseous fuel, such as a supplyconduit 19a leading into a gas range, and that the seat 11 is surroundedby the intake end of a connecting conduit 10b whose discharge end leadsinto a multi-stage gas burner, not shown.

When the user thereupon decides to admit a small stream of fuel to theconduit 10b, the valve member 12 is caused to move axially of the bore15 (for example, in response to axial or rotary movement of a knob orauother suitable handgrip means) and the ring 17 is compelled to passalong the obstruction 2@ to be subjected to increased compression sothat it offers greater resistance to axial movement of the valve member12. However, as soon as the center of the ring 17 moves upwardly andbeyond the innermost zone of the obstruction 20, it is subjected tolesser compression and its resistance to withdrawal of the valve member12 from the bore 15 decreases suddenly so that, and if the valve member12 is moved with unchanging force, it advances the ring 1'7 rapidlyalong and beyond the opening 18 and into the intermediate position ofFIG. 2 in which a small stream of fuel (arrows 10c) is free to ow atfull capacity through the bypass opening 18, through the recess 11b andinto the conduit 10b to be ignited in a first stage of the burner. Thegasket 13 moves away from the end face 11a as soon as the valve member12 leaves the position of FIG. 1 so that the discharge end of theopening 18 is exposed and fuel fiowing through the lower end of the bore15 is free to flow through the opening 1S and into the conduit 10b. Thevalve member 12 may remain in the position of FIG. 2 for a predeterminedperiod of time in order to permit satisfactory ignition of fuel in thefirst stage, whereupon the operator continues to move this valve memberin a direction to withdraw the extension 14 from the bore 15 until themember 12 reaches the valve opening position of FIG. 3 in which the ring17 is located at a level above the recess 11b so that a large stream offuel may flow through the upper end of the bore 15 (arrow 10d) and intothe connecting conduit 1b to enter the burner and to be ignited by theburning smaller fuel stream.

The situation is reversed when the valve member 12 is returned to theposition of FIG. 1. In the first stage of such movement, the ring 17enters the upper end of the bore 15 and is subjected to gradualcompression while moving along the inclined uppermost portion 111e ofthe internal surface of the stationary valve member 11i. Once it engagesthe valve member 10 at a level below the surface portion 10e, the ring17 is sufficiently compressed to prevent escape of fuel through theupper end of the bore 15, and this ring will seal the lower end of thebore from the bypass opening 18 as soon as it reaches the upper section22 of the obstruction 20. In response to further movement of the valvemember 12, the ring 17 moves along the sections 22, 21 and enters thelower portion of the bore 15 wherein it remains at the time the gasket13 reaches the end face 11a to provide a satisfactory seal againstescape of any fuel into the connecting conduit 10b.

It will be noted that the improved valve insures practicallyinstantaneous ow of a small gas stream from the conduit 11M, through thegap 1o and bypass opening 1S and into the conduit 10b as soon as theelastic ring 17 moves beyond the annular obstruction 20. The valve willpermit a small stream of gas to flow through the opening 18 withpractically instantaneous transition from a sealing to an exposingposition of the valve member 12 if the latter is biased by a suitablespring, not shown, which is free to expand substantially without anyloss in :cent'to the end portion 110e.

periphery of a circle which is adjacent to the section 22.

The rate at which the gas flows to the conduit b when the valve member12 assumes the intermediate position of FIG. 2 will also depend on thecross section of the bypass openingor openings 18. In certain instances,we may provide suitable nozzles which are inserted into the opening or`openings 18 to produce the well known venturi effect.

When.the ring 17 moves along the end portion 10e of the internal surfacebounding the bore 15, it is permitted to expand very rapidly and itsexpansion produces a component of force which tends to expel theextension 14 lfrom the bore. Thus, the effect of the end portion lite isthe same as that of the section 22.

The conduits 10a, 10b were omitted in FIGS. 2 and 3 for the sake ofclarity. The valves of FIGS. 4-12 are connected with similar conduits,and it is always assumed that the conduit 10a contains a supply ofcompressed gaseous fuel and that the conduit 10b connects vthe valvewith a multi-stage gas burner.

FIGS. I4 to 6 illustrate anmodiiied valve whose parts are videntified bythe numerals used in FIGS. l to 3 but each "precededfby a digit 1. Theinteral surface of the stationary valve member 110 which'surrounds thebore 115 is Vformed' with an annular groove 114b arranged to receive aportion of a compressed sealing ring 117, and this ring abuts againstthe peripheral surface 11441 of the extension 114.which forms part of amovable valve member 112. In the valve closing position of FIG. 4, thegasket I113 abuts against the end face 111a of the valve seat 111,

and the ring 117 abuts against the first section 121 of the surface onan annular obstruction or bead 120 which is provided onl the extension114 and whose second surface .section 122is adjacent to the dischargeend of a bypass opening 118 provided in the extension 114 andcomrnunicating with the annular gap 116. The opening 118 communicateswith the lower vend of the bore 115 but is free to communicate with therecess 111b as soon as the valve `member 112 is moved to theintermediate position of FIG. 5 in which the-ring 117 abuts against thatzone of the peripheral surface 114a which is immediately adja- A smallstream of gas is then free to iiow in the direction indicated by arrows110C.

'When the valve member 112 is moved to the valve opening position ofFIG. 6, a large stream of gas ilows in the direction indicated by an'arrow 11051 and the ring 11'7 is free to'expand because the extension114 is moved .above the level of the groove 114b. i

When the valve member 112 moves upwardly, a

-viewed in FIG. 4, the ring 117 is compressed rst by the .surfacesection'121 and thereupon by the surface section A122,'but is permittedto expand gradually while in engage- -ment with the section 122. Suchexpansion is terminated when the obstruction 120 passes beyond the ringand,

while the ring engages the section 122, its resistance to movement ofthe member 112 to the valve opening position of FIG. 6 decreasessuddenly so that the discharge end of the bypass opening 113 is exposedalmost in- ;stantaneously to deliver a small stream of fuel to the non-`illustrated multi-stage burner wherein the fuel is ignited inthe wellknown manner, for example, by a pilot light or in another suitable way.

. A second sudden drop in resistance which the ring `117 offers towithdrawal of the extension 114 from the .bore 115 takes `place when thesurface portion 110e :moves upwardly and beyond the position of FIG. 5.This effect is the same as when the ring 117 engages the section 122,i.e., the ring is permitted to expand d very rapidly and its expansionproduces a component of force which is parallel with the axis of theextension 114 and which will tend to push the extension 114 out of thebore 115.

FIGS. 7 to 9 illustrate a third valve wherein all parts analogous tothose described in connection with FIGS. l to 6 are identified by thenumerals used in FIGS. l to 3 but each preceded by the digit 2. In thisvalve, the obstruction 20 is replaced by a different obstruction 230which assumes the form of an annular depression or groove machined intothe internal surface of the stationary valve member 210 andcommunicating with the gap 216. The bypass opening 218 communicates withthe depression 230 and with the annular recess 211b of the valve seat211. A portion of the sealing ring 217 is accommodated in an annulargroove 214b which extends inwardly from the peripheral surface 214e ofthe extension 214 forming part of the movable valve member 212. In the'valve closing position of the member 212 (FIG. 7), the gasket 213 abutsagainst the end face 211a of the valve seat 211 and the compressedelastic ring 217 bears against the internal surface of the valve member210 just below the annular depression 230. Thus, the intake end of thebypass opening 21S is sealed from the lower end of the bore 215, and thedischarge end of the opening 218 is simultaneously sealed from theburner by the gasket 213 which abuts against the end face 2:11a. Thehorizontal symmetry plane of the ring 217 is then located at a levelbelow the lower edge of the depression 230.

When the Valve member 212 is moved toward the intermediate position ofFIG. 8, the ring 217 expands into the depression 230 and continues toseal the bypass opening 213y from the lower end of the bore 215.However, as the member 212 continues to move toward the position of FIG.8, the ring 217 is permitted to expand suddenly as soon as it reachesthe surface 210e which constitutes the upper zone of the internalsurface surrounding the bore 215 so that the intake end of the opening213 is exposed and permits a small stream of fuel (arrows 210C) to owtoward the burner. This intermediate position of the valve member 212 isshown in FIG. 8. The lower portion of the surface 210e is nearer to theperipheral surface 214a than the upper portion of the surface 210e sothat the effect is the same as that of the obstruction 20 or 120. Thedepression 230 assists the lower portion of the surface 210e to increasethe resistance of the ring 217 against withdrawal of the extension 214from the bore 215, i.e., the force which moves the valve member 212 mustovercome the resistance of the ring 217 when the latter extends into thedepression 230 by compressing the ring so that it can move along theannular edge between the wall bounding the depression 230 and the lowerend of the surface 210e. As the ring 217 expands while moving along theoutwardly diverging portion of the surface 210e, its expansion producesa component of force which will tend to move the valve member 212upwardly toward the valve opening position of FIG. 9 in which a largestream of gaseous fuel is permitted to liow through the bore 215 andthrough the recess 211b (arrow 210d) toward the non-illustrated burner.

The bypass opening 218 comprises a radial section which extendsoutwardly from the bottom zone of the depression 230 and an axialsection which communicates with the radial section and with the recess211b inwardly of the seat 211. If the depression 230 is comparativelydeep, the radial section of the bypass opening 218 may be dispensed withso that the axial section provides a direct channel between thedepression and the recess 211k.

Referrring finally to FIGS. l0 to l2, there is shown a fourth valvewhich is analogous to that of FIGS 7 to 9 used in FIGS. l to 3 but eachpreceded by a digit 3. The

annular depression 330 is provided in the peripheral surface S14-a ofythe extension 314, and this depression communicates with one or moreradial bypass openings 31S machined into the extension 31d of themovable valve member 312 and communicating with the lower (intake) endof the bore 31S. The gap 316 accommodates a portion of a compressedelastic sealing ring 317 which extends into an annular groove 314bprovided in the internal surface of the stationary valve member 3ft).The construction of the seat 311 and of the gasket 313 is the same as inFGS. 1 to 9.

In the valve closing position of the valve member 312 (FIG. l), the ring317 bears against a cylindrical surface portion of the extension 314 andthereby seals the discharge end of the bypass opening 318 from therecess 31112. When the valve member 312 then moves toward theintermediate position of FIG. l1, the ring 317 enters the depression 330and is thereby permitted to expand while continuing to seal the opening318 from the recess 311k. In response to further withdrawal of theextension 314 from the bore 3&5, the ring moves along the upper portionof the downwardly and inwardly diverging surface 310e and is compressedjust prior to renewed expansion as it moves beyond the position of FIG.1l and toward the valve opening position of FIG. l2 in which it permitsa large stream of gaseous fuel (arrow 310d) to fiow toward the burner.The arrows 310C illustrate in FlG. l1 the direction of fuel flow whenthe discharge end of the bypass opening 318 is permitted to communicatewith the recess 311b.

Without further analysis, the foregoing will so fully reveal the gist ofthe present invention that others can, by applying current knowledge,readily adapt it for various applications without omitting featuresthat, from the standpoint of prior art, fairly constitute essentialcharacteristics of the generic and specific aspects of this inventionand, therefore, such adaptations should and are intended to becomprehended within the meaning and range of equivalence of thefollowing claims.

What is claimed as new and desired to be secured by Letters Patent is:

1. A valve, particularly for controlling the fiow of fuel to amulti-stage gas burner, comprising a first valve member having a b-orewith a first and a second end and an internal surface surrounding saidbore; a second valve member having a peripheral surface spaced from anddefining an annular gap with said internal surface, said second valvemember being movable axially in a first direction from t-he first towardthe second end of said bore into a valve closing position and in asecond direction counter t-o said first direction to assume a Valveopening position, one of said valve members having an annular depressioncommunicating with said gap and a bypass opening communicating with saiddepression, said annular depression having a predetermined width in theaxial direction of said second member; and a normally compressed elasticsealing ring received in sa-id gap and secured to the other Valve memberso as t-o engage the surface -of said one valve member between saidopening and one end of said bore when the second valve member assumessaid valve closing position, said sealing ring having a width in saidaxial direction greater than said width of said depression, the surfaceof said one valve member having a first annular porti-on adjacent tosaid depression and located between said depression and the other end ofsaid bore and a second annular portion separated from said depression bysaid first annular portion, said second annular portion being moredistant from said other valve member than said first annular portion sothat when the second valve member moves in said second direction, thering expands into said depression entirely closing and thereby sealingthe same, is then compressed while engaging said first annular portion,and is permitted to expand suddenly toward said second annular portionwith smultaneous sudden reduction in its resistance to movement of thesecond valve member in said second direction.

2. A valve, particularly for controlling the flow of fuel to amulti-stage gas burner, comprising a first valve member having a borewith an intake end and a discharge end and an internal surfacesurrounding said bore; a second valve member having a peripheral surfacespaced from and defining an annular gap with said internal surface, saidsecond valve member being movable axially in a first direction from thedischarge end toward the intake end of said bore into a valve cl-osingposition and in a second direct-ion counter to said first direction toassume a valve opening position, said first valve member having anannular depression provided in said internal surface and communicatingwith said gap intermediate t-he ends of said bore and a bypass openinghaving an intake end communicating with said depression, said annular.depression having a predetermined width in the axial direction of saidsecond member, said internal surface having a first annular portionimmediately adjacent to said depression and located between saiddepression and said discharge end and a second annular portionimmediately adjacent to said first annular portion and located betweenthe discharge end and said first annular portion, said seeond annular.portion being more distant from said second valve member than saidfirst annular portion; and a normally compressed elastic sealing ringreceived in said gap and secured to said second valve member to engagesaid internal surface intermediate said depression and the intake end ofsaid bore when the second valve member assumes said valve closingposition, said seal-ing ring having a width in said axial directiongreater than said width of said depression, said ring being first causedto expand while entering said depression entirely closing and therebysealing the same when the second valve member moves in said seconddirection and the ring Ais Vthereupon compressed while moving along saidfirst annular portion prior to sudden expansion tow-ard said 'secondannular portion to reduce its resistance to lmovement of the secondvalve member in said second direction.

3. A Valve as set forth in claim 2, wherein said bypass opening has asecond end which communicates with vthe discharge end of said bore inall positions of said second valve member. Y

4. A valve, particularly for controlling the flow of fuel to amulti-stage gas burner, comprising a rst valve mem ber having a borewith an intake end and a discharge end and an internal surfacesurrounding said bore; a second valve member having a peripheral surfacespaced from and defining an annular gap with said Ainternal surface,said second valve member being movable axially in a first direction fromthe discharge end toward the intake end of said bore into a valveclosing position and in a second direction counter to said firstdirection to assume a valve opening position, said second valve memberhaving an annular depression provided in said peripheral sur face andcommunicating with said gap intermediate the ends of said bore and abypass opening having a discharge end communicating with saiddepression, Vsaid annular depression having a predetermined width in theaxial direction of said second member, said peripheral surface having afirst annular portion immediately adjacent to said depression andlocated between said depression and the intake end of said bore and asecond annular portion immediately adjacent to said first annularportion and located between the intake end of said bore and said firstannular portion, said second annular portion being more distant fromsaid internal surface than said first annular portion; and a normallycompressed elastic sealing ring received in said gap and secured to saidfirst valve member to engage said peripheral surface intermediate saiddepression and the discharge end of said bore when the second valvemember assumes said valve closing position, said sealing ring having aWidth in said axial direction greater than said Width -of saiddepression, said ring being rst caused to expand into said depressionentirely closing and thereby sealing the same While the second valvemember moves in said second direction, to thereupon undergo compressionWhile in engagement with said iirst annular port-ion, and to expandsuddenly toward said second annular portion with simultaneous reductionin its resistance to movement of the second valve member in said seconddirection so that the discharge end of said bypass Aopening is suddenlyfree to communicate with the discharge end of said bore.

5. A valve as set forth in claim 4, wherein said bypass opening has asecond end which communicates with the E@ intake end of said bore in al1positions -of said second vaive member.

References Cited by the Examiner UNITED STATES PATENTS 820,178 5/1906Buerkle 137-625.26 2,542,390 2/1951 Brown 137-625-48 2,574,851 11/1951Wagner 137-6253 2,693,201 11/1954 Page 137-625-33 X FOREIGN PATENTS639,538 4/ 1962 Canada.

M. CARY NELSON, Primary Examiner.

1. A VALVE, PARTICULARLY FOR CONTROLLING THE FLOW OF FUEL TO AMULTI-STAGE GAS BURNER, COMPRISING A FIRST VALVE MEMBER HAVING A BOREWITH A FIRST AND A SECOND END AND AN INTERNAL SURFACE SURROUNDING SAIDBORE; A SECOND VALVE MEMBER HAVING A PERIPHERAL SURFACE SPACED FROM ANDDEFINING AN ANNULAR GAP WITH SAID INTERNAL SURFACE, SAID SECOND VALVEMEMBER BEING MOVABLE AXIALLY IN A FIRST DIRECTION FROM THE FIRST TOWARDTHE SECOND END OF SAID BORE INTO A VALVE CLOSING POSITION AND IN ASECOND DIRECTION COUNTER TO SAID FIRST DIRECTION TO ASSUME A VALVEOPENING POSITION, ONE OF SAID VALVE MEMBERS HAVING AN ANNULAR DEPRESSIONCOMMUNICATING WITH SAID GAP AND A BYPASS OPENING COMMUNICATING WITH SAIDDEPRESSION, SAID ANNULAR DEPRESSION HAVING A PREDETERMINED WIDTH IN THEAXIAL DIRECTION OF SAID SECOND MEMBER; AND A NORMALLY COMPRESSED ELASTICSEALING RING RECEIVED IN SAID GAP AND SECURED TO THE OTHER VALVE MEMBERSO AS TO ENGAGE THE SURFACE OF SAID ONE VALVE MEMBER BETWEEN SAIDOPENING AND ONE END OF SAID BORE WHEN THE SECOND VALVE MEMBER ASSUMESSAID VALVE CLOSING POSITION, SAID SEALING RING HAVING A WIDTH IN SAIDAXIAL DIRECTION GREATER THAN SAID WIDTH OF SAID DEPRESSION, THE SURFACEOF SAID ONE VALVE MEMBER HAVING A FIRST ANNULAR PORTION ADJACENT TO SAIDDEPRESSION AND LOCATED BETWEEN SAID DEPRESSION AND THE OTHER END OF SAIDBORE AND A SECOND ANNULAR PORTION SEPARATED FROM SAID DEPRESSION BY SAIDFIRST ANNULAR PORTION, SAID SECOND ANNULAR PORTION BEING MORE DISTANTFROM SAID OTHER VALVE MEMBER THAN SAID FIRST ANNULAR PORTION SO THATWHEN THE SECOND VALVE MEMBER MOVES IN SAID SECOND DIRECTION, THE RINGEXPANDS INTO SAID DEPRESSION ENTIRELY CLOSING AND THEREBY SEALING THESAME, IS THEN COMPRESSED WHILE ENGAGING SAID FIRST ANNULAR PORTION, ANDIS PERMITTED TO EXPAND SUDDENLY TOWARD SAID SECOND ANNULAR PORTION WITHSIMULTANEOUS SUDDEN REDUCTION IN ITS RESISTANCE TO MOVEMENT OF THESECOND VALVE MEMBER IN SAID SECOND DIRECTION.